Synthesis and Electrochemical Properties of Ni Doped Spinel LiNi_xMn_(2-x)O_4 (0 ≤ x ≤ 0.5) Cathode Materials for Li-lon Battery

摘要

Spherical pristine LiMn_2O_4 and Ni doped LiNi_xMn_(2-x)O_4 (x=0.1, 0.2, 0.3, 0.4, 0.5) cathode materials for lithium ion battery with high first cycle discharge capacity and excellent cycle performance were synthesized using the solution-combustion technique. XRD analysis revealed peak shift towards higher angle and lattice shrink as a result of Ni doping. CSAFM result confirms LiNi_(0.5)Mn_(1.5)O_4 provides higher current of 10nA than pristine LiMn_2O_4 of 0.05nA. The EIS result displays that small Ni content (x=0.1, 0.2) doping reduced the impedances of pristine LiMn_2O_4. The composition LiNi_(0.1)Mn_(1.9)O_4 exhibits higher capacity and better cycleability than other Ni content compositions. Charge/discharge cycling result shows that Ni substitution substantially improved the capacity retention of LiMn_2O_4. All Ni doped LiNi_xMn_(2-x)O_4 (x= 0.1, 0.2, 0.3, 0.4, 0.5) compositions are able to retain 99% of their respective first cycle discharge capacities, whereas LiMn_2O_4 retains only 60% of its first cycle discharge capacity of 122 mAh/g after 50 cycles.